JP6709499B2 - Infrared transparent glass - Google Patents

Description

The present invention relates to infrared transmitting glass used for infrared sensors and the like.

In-vehicle night vision systems, security systems, etc. are equipped with infrared sensors that are used to detect living bodies at night. Since the infrared sensor senses infrared rays emitted from a living body and having a wavelength of about 8 to 14 μm, an optical element such as a filter or a lens that transmits infrared rays in the wavelength range is provided in front of the sensor unit.

Ge and ZnSe are mentioned as a material for the above optical elements. Since these are crystalline bodies, they are inferior in workability, and it is difficult to process them into complicated shapes such as aspherical lenses. Therefore, there are problems that it is difficult to mass-produce and it is difficult to downsize the infrared sensor.

Therefore, chalcogenide glass has been proposed as a glassy material that transmits infrared rays having a wavelength of about 8 to 14 μm and is relatively easy to process (see, for example, Patent Document 1).

JP, 2009-161374, A

Since the infrared ray transmittance of the glass described in Patent Document 1 is remarkably lowered at a wavelength of 10 μm or more, the infrared ray sensor may not function sufficiently because the infrared ray emitted from the living body is inferior in sensitivity.

In view of the above, it is an object of the present invention to provide glass that has excellent infrared transmittance and is suitable for infrared sensor applications.

As a result of intensive studies by the present inventors, they have found that the above problem can be solved by a chalcogenide glass having a specific composition.

That is, the infrared transparent glass of the present invention is, in mol %, Ga 0 to 89% (excluding 0%), Te 11 to 90%, S 0 to 89% (excluding 0%), Ge+Sn+Ag+Cu+Bi+Sb 0. ˜50%, and F+Cl+Br+I 0-50%. In addition, in this specification, "○+○+..." means the total amount of the content of each applicable component.

The infrared transparent glass of the present invention preferably contains substantially no Cd, Tl or Pb.

The infrared transmitting glass of the present invention preferably has an infrared absorption edge wavelength of 20 μm or more at a thickness of 2 mm. In the present invention, the “infrared absorption edge wavelength” means a wavelength at which the light transmittance is 0.5% in the infrared region having a wavelength of 8 μm or more.

The optical element of the present invention is characterized by using the above infrared transmitting glass.

An infrared sensor of the present invention is characterized by using the above optical element.

The infrared transparent glass of the present invention has excellent infrared transmittance and is suitable for infrared sensor applications.

The infrared transparent glass of the present invention is, in mol %, Ga 0 to 89% (excluding 0%), Te 11 to 90%, S 0 to 89% (excluding 0%), Ge+Sn+Ag+Cu+Bi+Sb 0 to 50. %, and F+Cl+Br+I 0 to 50%. The reason for defining the glass composition in this way will be described below. In the following description of the content of each component, "%" means "mol %" unless otherwise specified.

Ga is an essential component for forming the glass skeleton. The Ga content is 0 to 89% (excluding 0%), preferably 5 to 70%, and more preferably 10 to 60%. If the Ga content is too low, vitrification becomes difficult. On the other hand, if the Ga content is too high, Ga-based crystals are deposited and infrared rays are less likely to pass through, and the raw material cost tends to increase.

Te, which is a chalcogen element, is an essential component that forms the glass skeleton. The content of Te is 11 to 90%, preferably 15 to 85%, and more preferably 30 to 80%. If the Te content is too low, vitrification tends to be difficult. On the other hand, if the Te content is too high, Te-based crystals are deposited and infrared rays are difficult to transmit.

S, which is also a chalcogen element, is an essential component that enhances the thermal stability (stability of vitrification) of glass. The content of S is 0 to 89% (excluding 0%), preferably 5 to 70%, and more preferably 10 to 60%. If the S content is too low, vitrification becomes difficult. On the other hand, if the content of S is too large, the infrared absorption edge wavelength shifts to the short wavelength side, and the infrared transmission characteristics are likely to deteriorate.

Ge, Sn, Ag, Cu, Bi and Sb are components that enhance the thermal stability of the glass without deteriorating the infrared transmission characteristics. The content of Ge+Sn+Ag+Cu+Bi+Sb is 0 to 50%, preferably 0 to 50% (excluding 0%), more preferably 1 to 40%, and further preferably 2 to 30%. It is preferably 3 to 25%, particularly preferably 5 to 20%. If the content of Ga+Sn+Ag+Cu+Bi+Sb is too small or too large, vitrification becomes difficult. The content of each component of Ga, Sn, Ag, Cu, Bi and Sb is 0 to 50%, preferably 0 to 50% (excluding 0%), and 1 to 40%. Is more preferable, 2 to 30% is still more preferable, 3 to 25% is particularly preferable, and 5 to 20% is most preferable. Among them, Ge, Ag or Sn is preferably used because the effect of enhancing the thermal stability of the glass is particularly large.

F, Cl, Br and I are also components that enhance the thermal stability of the glass. The content of F, Cl, Br, I is 0 to 50%, preferably 1 to 40%, more preferably 1 to 30%, further preferably 1 to 25%, It is particularly preferably 1 to 20%. When the content of F+Cl+Br+I is too large, it becomes difficult to vitrify and the weather resistance tends to decrease. The content of each of F, Cl, Br, and I is 0 to 50%, preferably 1 to 40%, more preferably 1 to 30%, and 1 to 25%. Is more preferable, and 1 to 20% is particularly preferable. Among them, I is preferably used because it is possible to use the elemental raw material and the effect of enhancing the thermal stability of the glass is particularly large.

The infrared transparent glass of the present invention may contain the following components in addition to the above components.

Zn, In and P are components that expand the vitrification range and enhance the thermal stability of the glass. The content of each is preferably 0 to 20%, and more preferably 0.5 to 10%. If the content of these components is too large, vitrification becomes difficult.

Se and As are components that expand the vitrification range and enhance the thermal stability of the glass. The content of each is preferably 0 to 10%, and more preferably 0.5 to 5%. However, since these substances are toxic, it is preferable not to contain them from the viewpoint of reducing the influence on the environment and the human body.

It is preferable that the infrared transparent glass of the present invention does not substantially contain toxic substances Cd, Tl and Pb. In this way, the impact on the environment can be minimized. Here, "substantially free from" means not intentionally added to the raw material, and does not exclude inclusion of impurity levels. Objectively, the content of each component is preferably less than 0.1%.

The infrared transparent glass of the present invention is excellent in infrared transmittance at a wavelength of about 8 to 18 μm. An infrared absorption edge wavelength is mentioned as an index for evaluating the infrared transmittance. It can be judged that the larger the infrared absorption edge wavelength, the better the infrared transmittance. The infrared absorption edge wavelength of the infrared transmission glass of the present invention at a thickness of 2 mm is preferably 20 μm or more, and more preferably 21 μm or more.

The infrared transparent glass of the present invention can be produced, for example, as follows. First, raw materials are prepared so as to have a desired composition. The raw material is put into a quartz glass ampoule that has been evacuated while heating, and the tube is sealed with an oxygen burner while being evacuated. The infrared ray transmitting glass of the present invention is obtained by holding the sealed quartz glass ampoule at about 650 to 1000° C. for 6 to 12 hours and then rapidly cooling it to room temperature.

As a raw material, an elemental raw material (Ga, Te, S, Ag, I, etc.) may be used, or a compound raw material (Ga ₂ Te ₃ , Ga ₂ S ₃ , AgI, etc.) may be used. It is also possible to use these together.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

Tables 1 and 2 show examples of the present invention and comparative examples, respectively.

Each sample was prepared as follows. Raw materials were mixed so that the glass compositions shown in Tables 1 and 2 were obtained to obtain raw material batches. The quartz glass ampoule washed with pure water was evacuated while heating, then the raw material batch was charged, and the quartz glass ampoule was sealed with an oxygen burner while evacuating.

The sealed quartz glass ampoule was heated in the melting furnace at a rate of 10 to 20° C./hour to 650 to 1000° C. and then held for 6 to 12 hours. During the holding time, the quartz glass ampoule was turned upside down every 2 hours and the melt was stirred. Then, the quartz glass ampoule was taken out of the melting furnace and rapidly cooled to room temperature to obtain a sample.

The obtained sample was subjected to X-ray diffraction, and it was confirmed from the diffraction spectrum whether or not it was vitrified. In the table, those which are vitrified are indicated by "○" and those which are not vitrified are indicated by "x". In addition, the light transmittance at a thickness of 2 mm was measured for each sample, and the infrared absorption edge wavelength was measured.

As shown in Table 1, the samples of Examples 1 to 10 are vitrified, have an infrared absorption edge wavelength of 24.1 to 24.3 μm, and have good light transmittance in the infrared region near the wavelength of 8 to 18 μm. Was shown.

On the other hand, the samples of Comparative Examples 1 to 3 were not vitrified, and the light transmittance was almost 0% in the wavelength range of 2 to 24 μm.

INDUSTRIAL APPLICABILITY The infrared transparent glass of the present invention is suitable as an optical element such as a cover member for protecting the sensor part of an infrared sensor and a lens for focusing infrared light on the sensor part.

Claims (6)

In mole%, Ga 15 ~89%, Te 11~90%, ( not including the proviso 0%) S 0~89%, characterized by containing the Ge + Sn + Ag + Cu + Bi + Sb 0~50%, and F + Cl + Br + I 0~50 % Infrared transparent glass. The infrared transparent glass according to claim 1, which is substantially free of Cd, Tl and Pb. The infrared transmission glass according to claim 1 or 2, wherein the infrared absorption edge wavelength at a thickness of 2 mm is 20 µm or more. It is chalcogenide glass, The infrared transmission glass as described in any one of Claims 1-3 characterized by the above-mentioned. Optical element characterized by using an infrared transmitting glass according to any one of claims 1-4. An infrared sensor comprising the optical element according to claim 5 .